In the continuous casting of metals, the molten liquid is contained in a refractory lined ladle, tundish, or similar vessel. In most cases the metal flows out through an orifice or nozzle in the bottom of the vessel. There are three methods by which the flow of molten material is normally interrupted:
(1) a stopper or plug is inserted from above through the reservoir of liquid;
(2) the use of a valve mechanism of which the nozzle is a part thereof, and which is commonly referred to as a "slide gate"; and
(3) the use of a chill plug which is inserted from below. The latter method, to which this invention applies, is generally preferred for the continuous casting of steel billets. In such an operation the chill plug is usually a conical block of copper attached to a bent steel bar. The operator, using the bar as a handle, inserts the plug in the nozzle or orifice and holds it there until the liquid solidifies in the nozzle.
The interruption of flow is often necessitated by emergency conditions, such as a power or water supply failure which affects the casting machine operation. The manual insertion of the chill plug as described above has several disadvantages, the most important being the risk that the operator may be splashed by molten metal and the time lapse between the occurrence of a fault and the interruption of the flow. The operator is generally unaware of the fault until it has a visible effect, such as a sudden change in the level of the meniscus in the mold. This delay is extended by the operator's response time. Manual insertion of the chill plug has heretofore been considered necessary because clearance between the tundish and mold is usually less than sufficient to permit the installation of common mechanical devices capable of performing the operation.